(1) Field of the Invention
The present invention relates to a system, and a method for using such a system, comprising active position transmitters to determine the position of a moveable platform. More specifically, the present invention relates to a method of using active transmitters to determine the position of an elevator in a hoistway.
(2) Description of Related Art
A Positioning Reference System (PRS) is component of an elevator control system that provides fast and accurate position measurement of a moveable platform, in particular an elevator car, in a hoistway. Two problems associated with optical position reference systems, especially those for elevator Positioning Reference Systems, arise as the result of ambient light interference, especially in a glass hoistway, and reduced performance under emergency conditions due to fire or smoke. These deficiencies are fundamental when using optical detection of a passive reflector containing coded information.
What is therefore needed is a high-accuracy positioning means with low cost for installation, and maintenance.